Metabolic roles of carnitine expressed through the carnitine acetyltransferase system in Candida pintolopesii |
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| Institution: | 1. Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran;2. Students’ Scientific Research Center (SSRC), Tehran University of Medical Sciences (TUMS), Tehran, Iran;3. Department of Traditional Medicine, School of Persian Medicine, Tehran University of Medical Sciences, Tehran, Iran;4. Faculty of Land and Food Systems, University of British Columbia, Vancouver, Canada;1. Department of Chemical Engineering, Monash University – Clayton Campus, Wellington Road, Clayton, Victoria 3800, Australia;2. Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia;3. Centre for Materials and Surface Science, Department of Chemistry and Physics, La Trobe University, Melbourne, Victoria 3086, Australia;4. Monash Centre for Electron Microscopy, Monash University- Clayton Campus, Wellington Road, Clayton, Victoria 3800, Australia;1. Cooperative Course of Nano-Medical Device Engineering, Hallym University, Chuncheon, Gangwon-do, 24252, Republic of Korea;2. Department of Materials Science and Engineering, Hallym University, Chuncheon, Gangwon-do, 24252, Republic of Korea;3. Integrative Materials Research Institute, Hallym University, Chuncheon, Gangwon-do, 24252, Republic of Korea;4. Department of Burn Surgery, Burn Center, Hangang Sacred Heart Hospital, Hallym University Medical Center, Seoul, 150-715, Republic of Korea;5. Department of Pathology, Collage of Medicine, Hallym University, Chuncheon, Gangwon-do, 24252, Republic of Korea;6. Department of Chemical Engineering, Hongik University, Seoul, 04066 Republic of Korea;1. Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, North Third Ring Road 15, 100029, Beijing, China;2. Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Denickestrasse 15, D-21073 Hamburg, Germany |
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| Abstract: | - 1.1. The carnitine-responsive mutant yeast, Candida pintolopesii ATCC 26014 and the wild type strain (ATCC 22987) were used to investigate the role of carnitine and the carnitine acetyltransferase system.
- 2.2. 3H]l-Carnitine, supplied to the cells, was incorporated into acetylcamitine and 14C]pantothenate was incorporated into CoA and its derivatives.
- 3.3. Both bioautography and quantitative assays indicated that the relative amounts of CoA and acetylCoA were very different in the mutant and wild type cells.
- 4.4. The wild type yeast maintained an acetylCoA/CoA ratio of 0.33 ± 0.09 indicating that most of the CoA in the cell is in the free CoA form. Carnitine was not required to establish this ratio nor did its presence lower it further.
- 5.5. In contrast, the mutant cells contained a high acetylCoA/CoA ratio (12.8 ± 3.0).
- 6.6. In the mutant cells, carnitine lowered the ratio by decreasing the intracellular acetylCoA concentration and releasing free CoA.
- 7.7. These data indicated that wild type yeast possess an effective mechanism that is not related to the CAT system for regulating the acetylCoA/CoA ratio.
- 8.8. This mechanism appears to be lacking in the mutant. The CAT system decreased the acetylCoA/CoA ratio in the mutant cells but not to the value which is found in the wild type strain.
- 9.9. In both stains of Candida pintolopesii, in the presence of carnitine, an acetylcamitine pool can be created whose concentration exceeds that of acetylCoA.
- 10.10. The intracellular apparent equilibrium constant (Kapp) for carnitine acetyltransferase for wild type Candida pintolopesii ATCC 22987 was 0.73 ± 0.12, close to the established value of 0.6, indicating that the CAT system ran close to equilibrium.
- 11.11. The Kapp for the CAT system of the carnitine-responsive mutant yeast was 7.7 ± 1.7 indicating that this reaction was not at equilibrium.
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